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The present application contains a microfiche Appendix A. The total number of microfiche in Appendix A is 3 sheets. The total number of frames in Appendix A is 258.
The present invention relates to networks, and more particularly to generation of data used for network operation.
In some networks, network nodes store data which they use for proper operation. One example is squelch tables used in SONET rings. See Bellcore Generic Requirements document GR-1230-CORE (Issue 4, December 1998) incorporated herein by reference. In SONET, data between adjacent nodes are transmitted in modules called STS""s (synchronous transport signals). Each STS is transmitted on a link at regular time intervals (for example, 125 microseconds). If a failure occurs, an STS may have to be squelched to prevent misconnection. To accomplish squelching, a node in a SONET ring stores a squelch table. For each STS handled by the node, the squelch table specifies a node on which the STS is dropped, and a node on which the STS is added. If an STS contains sub-STS structures such as virtual tributaries (VT""s), the squelch table specifies, for each VT handled by the node, a node on which the VT is dropped and a node on which the VT is added.
Manual generation of squelch tables is a cumbersome and error-prone task. Therefore, squelch tables have been generated automatically. A separate computer, (for example, a UNIX station) can be connected to a node. The node requests data from other nodes regarding the STS""s added and dropped on the other nodes, and provides these data to the computer. The computer constructs a squelch table for each node on the ring. The computer sends the squelch tables to the node to which the computer is connected. This node distributes the squelch tables to the other nodes on the ring.
It is desirable to facilitate generation of data used for network operation, and make the data generation more robust.
When failure occurs in a SONET ring, traffic can be switched from a xe2x80x9cworkingxe2x80x9d channel to a xe2x80x9cprotectionxe2x80x9d channel (a redundant channel) and transmitted in the opposite direction on the ring. When a SONET node receives traffic on the protection channel, the node may have to determine the format of the traffic to process the traffic correctly. For example, the node may have to extract the payload and re-transmit the payload further down the ring. The position of the payload in the SONET frame is defined by the frame""s overhead pointers. The pointers"" position in the frame depends on the type of the STS (e.g., a SONET OC48 link can carry an STS of type STS-48C or four byte-interleaved STS""s of type STS-12C; the pointers"" position will be different in each of these cases). Therefore, the node has to know the STS type.
Determining the STS type on the protection channel must be done quickly to avoid data loss or corruption. Quickly determining the STS type is a burden on the node""s circuitry.
It is desirable to provide techniques that would allow a network node to quickly and easily determine STS types on protection channels.
In some embodiments, each node generates data to be used for network operation. Therefore, failure of one node does not prevent data generation on other nodes. The network becomes more robust as a result.
Further, in some embodiments, each node generates the data. The data is not generated by a separate computer, and further the node generating the data need not be connected to a separate computer.
The invention is not limited to the features described above, or to any particular type of network. In some embodiments, the network satisfies at least one of the following conditions (A) and (B):
(A) in case of failure, traffic can be switched from one link to one or more other links, and when traffic is switched traffic can be squelched to prevent misconnection;
(B) data on each link are transmitted in data buckets, each data bucket being re-transmitted at regular intervals of time, each data bucket, when re-transmitted, being dropped on the same predetermined one or more nodes from the network.
One example of a data bucket is SONET""s STS or VT (virtual tributary). Another example is SDH""s STM (synchronous transport module) or VC (virtual container). SDH (synchronous digital hierarchy) is described in O. Kyas, xe2x80x9cATM networksxe2x80x9d (1995), incorporated herein by reference. See also W. J. Goralski, xe2x80x9cSONETxe2x80x9d (1997), incorporated herein by reference.
The node contains storage for storing xe2x80x9cfirstxe2x80x9d data (e.g. squelch tables), wherein for data received from the node""s one or more ports and/or transmitted on the one or more ports, the first data identifies at least one of other nodes on which the data is added to the network and/or at least one of other nodes on which the data is dropped from the network. An example of first data is a squelch table. The node generates the first data using circuitry which, besides generating the first data, also performs real time processing to accomplish communication of the node with the other nodes.
According to another aspect of the invention, a node has a cabinet containing circuitry for communicating with one or more other nodes over a network. The network satisfies at least one of the above conditions (A) and (B). The first data described above is generated by the circuitry in the cabinet and not by any circuitry outside the cabinet (e.g. not by a computer outside the cabinet).
According to another aspect of the invention, each node in the network generates the first data described above.
According to another aspect of the invention, each SONET ring node determines the STS types on SONET links not attached to the node. Each node determines the STS types in advance, before failure occurs. Each nodes stores the STS types in its storage. When a ring switch occurs, the switching procedures described in GR-1230-CORE inform ring nodes which node is switching traffic to a protection channel. Since the non-switching nodes already have in their storage the STS type on the link from which the traffic is being switched to the protection channel, the non-switching nodes know the STS type on the protection channel. Determining the STS type on the protection channel is thus quick and easy.
In some embodiments, to determine the STS types on links not attached to the node itself, the node requests other nodes to provide the STS types on links attached to the other nodes.
The invention is not limited to SONET embodiments. In some embodiments, in case of failure, traffic which is to be transmitted through a link not attached to a node can instead be re-directed and transmitted through the node. The node generates format information which indicates format of data on one or more links not attached to the node. (An STS type is one example of format information.) The format information will be used by the node in case of failure to process traffic which becomes transmitted through the node instead of one or more links not attached to the node. The format information is generated before the failure occurs.
Other embodiments and variations are within the scope of the invention, as defined by the appended claims.